1. Field of the Invention
The present invention relates to a piezoelectric component with leads used as, for example, a piezoelectric resonator or a piezoelectric filter, and more particularly, the present invention relates to a piezoelectric component with leads having an improved bonding structure between a terminal electrode and a lead terminal provided on a piezoelectric body.
2. Description of the Related Art
Various piezoelectric components including leads have been used as piezoelectric resonators and piezoelectric filters. Piezoelectric components including leads have been disclosed, for example, in Japanese Unexamined Utility Model Publication Nos. 2-326 and 6-58620, Japanese Unexamined Patent Application Publication No. 6-252683.
FIG. 17 is a perspective view showing a representative example of a conventional piezoelectric component with leads 51. The piezoelectric component with leads 51 includes a piezoelectric resonance element 52 and lead terminals 53 and 54.
As shown in FIG. 18, the piezoelectric resonance element 52 includes a piezoelectric plate 55 polarized uniformly in the thickness direction thereof. Vibration electrodes 56 and 57 are provided at the center of first and second main surfaces 55a and 55b of the piezoelectric plate 55, respectively, so as to be opposed to each other, with the piezoelectric plate 55 therebetween, on the top and bottom surfaces thereof. The vibration electrodes 56 and 57 are connected to lead-out electrodes 58 and 59, respectively. The lead-out electrodes 58 and 59 are connected to first and second terminal electrodes 60 and 61, respectively.
The terminal electrodes 60 and 61 are disposed in the vicinity of end portions of the piezoelectric plate 55. The lead terminals 53 and 54 include cup portions 53a and 54a, respectively, having a U-shaped cross section, and terminal lead-out portions 53b and 54b having a tabular shape. The inner surfaces of the cup portions 53a and 54a are bonded to the second and first terminal electrodes 61 and 60, respectively, using solder or a conductive adhesive.
To increase moisture resistance and shock resistance, the portions except the tip portions of the terminal lead-out portions 53b and 54b of the lead terminals 53 and 54 are coated with resin.
As describe above, the cup portions 53a and 54a are bonded to the terminal electrodes 61 and 60, respectively, using solder or a conductive bonding agent. Since solder or a conductive adhesive has fluidity during bonding, however, they flow along the inner surface of the cup portion 53a and 54a, and often extend to the lead-out electrodes 59 and 58, respectively. In an extreme case, the solder or conductive adhesive extends to the vibration electrodes 57 and 56, respectively. The resonance characteristics of piezoelectric component with leads 51 are, therefore, often deteriorates or experiences large fluctuation in characteristics.